For years, Iran and Western powers have had a relationship marked by distrust, suspicion and open animosity. The diplomatic gridlock between Iran and the West seems to have been fixed for decades. The rhetoric of Mahmoud Ahmadinejad, Iran’s sixth president, was filled with blatant insults and threats towards the United States and Israel. While protesting the crippling economic sanctions on Iran’s economy, he openly pushed for the advancement of Iranian nuclear technology.

With the election of President Hassan Rouhani this past June, however, the diplomatic tone has changed for the better. As the intensity of Western sanctions continues to threaten to cause social unrest, Iranian leadership have found themselves forced to the table, and concessions on the nuclear program seem more likely than ever. Just this past week, an agreement was reached that calls on Iran to limit its nuclear activities in return for lighter sanctions. Diplomats from Iran and the P5+1 (the five permanent members of the U.N. Security Council plus Germany), came to an initial agreement, making significant steps towards progress. Iranian and U.S. leaders, as well as officials from Russia, China, and the EU, have all expressed satisfaction with the deal.

However, there are many important figures and nations that have voiced adamant opposition to this accord. Many, skeptical of the Iranian reliability, reject engaging and negotiating with Iran. While halting any expansion of Iran’s nuclear program, the terms leave Iran’s atomic fuel-producing infrastructure intact. Israel is unsurprisingly incensed by this deal. Prime Minister Benjamin Netanyahu has been fierce in his distrust of Tehran and his belief that sanctions should only get tougher. Netanyahu called Sunday’s nuclear agreement a “historic mistake,” asserting that “the world has become a much more dangerous place because the most dangerous regime in the world has taken a significant step toward attaining the most dangerous weapon in the world.” Israel is far from alone in its disapproval. Israel and Gulf States alike firmly feel that continuing the sanctions could “force more meaningful Iranian concessions.” A reported collaboration between Saudi Arabia and Mossad, the Israeli intelligence and special operations agency, involves working on a powerful computer virus “more destructive” than the infamous Stuxnet malware in order to undermine Iran’s nuclear program. Regardless of the common interest, Saudi Arabia denies any official alliance; until the Palestinians are granted statehood, Saudi Arabia will not work with Israel. This purported tactic reflects the underlying mistrust both Israel and Saudi Arabia have towards the Iranian government, and why they feel weary towards the West agreeing to alleviate sanctions.

While there has been great focus on Israel’s opposition to the deal, there has been lesser attention paid to the regional implications. Despite the obvious fact that Iranian nuclear proliferation constitutes a direct threat to their populations, Arab countries have been largely excluded from the conversation. Nawaf Al-Obaid, an advisor to the Saudi government, lamented that Washington had not directly briefed the Saudi government about this deal. Sentiments of betrayal, deception, and distrust of the U.S. seem to have taken hold in Saudi Arabia. Beyond the threat of WMD capabilities, Arab countries fear that a deal will allow Iran to expand its regional influence. Support from the West and a growing economy in Iran will impact geopolitical security. Jamal Khashoggi, general manager of Al-Arabiya, stated, “The (Geneva) agreement has reduced the Iran problem to the nuclear level only, while its regional interference is of key concern to GCC countries.”

Saudi Arabia and other Gulf countries believe that Iran is not looking to substantially limit its nuclear capability, but rather to work out a comprehensive deal with the U.S. that would empower it to become more of a regional power. A Saudi official was quoted as saying, “Many in Saudi Arabia worry that Iran is not being sincere, and the worry during the negotiations was that any deal reached would mean Iran would widen their influence in the region-in countries like Lebanon and Bahrain-and become a bigger threat.”

Given the regional sectarian divide, Sunni Arab powers share fears about a shift in the regional balance of power towards Iran and its allies.Saudi Arabia, a central Sunni power, has several critical concerns about this deal with Iran. Saudi Arabia is especially aware of the economic threat posed by Iran, as an end to oil sanctions would mean more competition for Saudi petroleum exports. The alleviation of sanctions puts Iran in a position to “weaken Saudi authority by reasserting itself as a top OPEC force.” Like Israel and the West, Saudi Arabia is weary of a nuclear Iran and opposes Iran’s support for Shiite-affiliated terrorist groups and embattled Syrian president Bashar al-Assad’s regime. The Sunni-Shiite rift in the Muslim world comes into play regarding Iran’s nuclear program and the new interim agreement. Given the regional sectarian divide, Sunni Arab powers share fears about a shift in the regional balance of power towards Iran and its allies, such as the Iraqi government of Nuri Al-Maliki, the Lebanese movement Hezbollah, and Muslim Shia communities throughout the Gulf. Additionally, Iran’s influence in Iraq, which has risen since Saddam Hussein was ousted from power, is prominent in social, political, and economic spheres under the current Shia-led government.

Despite the range of tensions between these powers, relations with Iran are officially cordial. The diplomatic rhetoric of the Gulf States is cautiously optimistic about the deal, and Iran has reiterated its willingness to forge stronger ties with its neighbors. Iranian Foreign Minister Mohammad Javad Zarif said his government was willing to work together with Saudi Arabia in order “to promote peace” and achieve regional “stability.”

Looking forward, it is critical to keep Iran’s proliferation of nuclear arms in check and be cognizant of the implications of its growing regional power. Western countries who are eager to limit nuclear proliferation must also prepare for the rise of sectarianism and its threats to internal regional security. The Arab world and Iran have to work together closely at this crucial juncture. It is in everyone’s interest to establish stability to act preemptively as sectarian polarization intensifies, human rights conditions deteriorate, and a regional arms race is incited. Furthermore, in order to obtain any semblance of sustainable regional security order, the concerns of both regional and Western powers must be taken into account in dealings with Iran.